JPH05192965A - Mold for injection molding - Google Patents

Abstract

PURPOSE:To manufacture a mold for injection molding which can improve the appearance of a molded product. CONSTITUTION:A second sprue 9a is almost in parallel with a side face 8a of a recessed section 8 of a mold 11 close to the recessed section, and a section 9d closer to the recessed section from a plane including a shaft 9c of the second sprue 9a as the center and a section 9e on the opposite side are formed asymmetrically. The volume of the section 9d closer to said recessed section is made smaller than the volume of the section 9c on the opposite side to keep away from a recessed section 7b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die capable of improving the appearance quality of a molded product.

[0002]

2. Description of the Related Art A conventional injection mold is shown in FIG.
Those shown in are known.

This conventional injection molding die is mainly composed of a fixed side die 1 and a moving side die 2.
The molded product 4 is molded by injecting a resin material into the cavity molded in 2 through the sprue 3 molded on the fixed mold 1 side.

The molded product 4 has a convex portion 4 on the molded product body 4b.
a is formed, and the concave portion 5 forming the convex portion 4 a is formed in the fixed-side mold 1.

The sprue 3 is formed along the side surface 5a of the recess 5 with a constant space a, and its cross section perpendicular to the axis 3b has a substantially circular tapered shape. At the tip of this sprue 3, there is formed a pin gate 3a through which the resin material flows out of the sprue 3.

In such an injection molding die, after the resin material is filled, the dies 1 and 2 are released from each other, and the molded product 4 and the sprue 3 are formed.
The resin material inside is cut in the vicinity of the pin gate 3a, and the molded product 4 is taken out.

[0007]

However, in such a conventional injection molding die, the sprue 3 has the shaft 3b.
Since the cross section orthogonal to is substantially circular, the sprue 3
The axis 3b of the concave portion 5 has a constant distance a from the side surface 5a of the recess 5.
Is formed.

For this reason, after the mold release, the mark of the pin gate 3a is formed on the completed molded product 4 at a position separated from the convex portion 4a by an approximately constant amount a. When the mark of the pin gate 3a is formed at a position apart from the convex portion 4a as described above, there is a problem that the appearance quality of the molded product body 4 is impaired by being visible from almost all positions. In other words, if a trace of the pin gate 3a is formed in the vicinity of the convex portion 4a, the trace is hidden and is inconspicuous when viewed from the opposite side of the convex portion 4a.

Therefore, an object of the present invention is to provide an injection molding die capable of improving the appearance quality of a molded product.

[0010]

The present invention has been made in view of the above problems, and the invention described in claim 1 includes a molded article body and a convex portion protruding from the molded article body. An injection-molding die for molding a molded product having a concave portion for molding the convex portion and a sprue having a tapered shape along a side surface of the concave portion, wherein the sprue is substantially parallel to the side surface of the concave portion. And the portion near the recess and the portion on the opposite side are asymmetrical with respect to the plane including the axis of the sprue, and the volume of the portion near the recess is made smaller than the volume of the portion on the other side to form the recess. It is characterized in that it is an injection molding die formed so as to avoid.

Further, in the injection molding die according to the second aspect, the sprue molding portion forming the sprue is vertically divided along the axis of the sprue.

[0012]

According to the invention described in claim 1, the shape of the sprue is substantially parallel to the side surface of the recessed portion and is located on the side opposite to the portion near the recessed portion centering on a plane including the axis of the sprue. Since the portion has an asymmetrical shape, and the volume of the portion near the recess is smaller than the volume of the sprue on the opposite side to avoid the recess, the sprue is formed close to the recess. You can do it. Therefore, as compared with the conventional molded product body, a gate mark is formed near the convex portion, and the appearance quality can be improved.

According to the invention described in claim 2, in addition to the function of the invention described in claim 1,
Since the inner surface of the sprue can be divided and polished in a better condition than before when the sprue forming part is manufactured, the releasability can be improved without taking a large draft. For this reason, it is possible to reduce the escape gradient, reduce the volume of the sprue, and reduce the volume of the unnecessary non-molded product portion.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 9 show a first embodiment of the present invention. The same parts as those of the conventional example will be described with the same reference numerals.

First, the structure will be described. The injection molding die 6 of the first embodiment has a fixed side die 10 and a moving side die 2.
It is mainly composed of and, as shown in FIG.
This fixed side mold 1 is inserted into the cavity formed by 0 and 2.
The molded product main body 7a and the convex portion 7b protruding from the molded product main body 7a are caused by inflowing the resin material from the first sprue 13 and the runner 14 formed on the 0 side through the plurality of second sprues 9a. A plurality of molded products 7 having the same are molded.

Of these, the fixed-side die 10 has a concave portion 8 for molding the convex portion 7b as shown in FIG.
The second sprue 9a tapered along the side surface 8a of the
And a second sprue molding portion 9 that forms

The second sprue molding portion 9 is composed of a recessed member 11 and a member 12 on the opposite side, which are vertically divided along the shaft 9c of the second sprue 9a.
The second sprue 9a is substantially parallel to the side surface 8a of the recess 8 and is opposite to the portion 9d near the recess with a plane including the axis 9c of the second sprue 9a as the center.
e and a have an asymmetrical shape.

The volume of the portion 9d near the recess is made smaller than the volume of the portion 9e on the opposite side so as to avoid the recess 8.

A pin gate 13 is formed at the tip of the opposite side portion 9e so that the resin material can flow out from the sprue 3 (see FIGS. 4 to 6). On the other hand, a portion corresponding to the pin gate 13 is not formed at the tip of the recessed portion 9d (see FIGS. 7 to 9).

The position of the pin gate 13 is the same as that of the recess 8
Is disposed at a constant distance b from the side surface 8a of the.

Next, the operation of the first embodiment will be described.

The shape of the second sprue 9a is substantially parallel to the side surface of the recess 8 and the shaft 9c of the second sprue 9a.
The portion 9d near the concave portion and the portion 9e on the opposite side have an asymmetrical shape with a plane including the center as a center, and the volume of the portion 9d near the concave portion is made smaller than the volume of the portion 9e on the opposite side to form the concave portion 8. Since it is formed so as to avoid, the second sprue 9a can be formed close to the concave portion 8.

Therefore, in comparison with the conventional completed molded product, the completed molded product 7 of the first embodiment has a gate mark 14 near the convex portion 7b. As shown in FIG. 3, when the gate mark 14 is formed in the vicinity of the convex portion 7b, it is not so conspicuous and cannot be seen because it is behind the convex portion 7b particularly from the position of the line of sight e in FIG. Therefore, the appearance quality of the molded product 7 can be improved.

When manufacturing the second sprue molding part 9,
As shown in FIGS. 4 to 9, by dividing the member 11 closer to the recess and the member 12 on the opposite side to expose the inner surface of the sprue of each member 11, 12, it is easy to perform electric discharge machining, and then shallow Since only the part needs to be polished, polishing work can be done easily.

Since the polishing work is facilitated as described above, the precision of the polishing surface is improved, so that the mold release is facilitated, and the relief gradient c of the second sprue 9a is greatly increased as shown in FIG. You don't have to take it. Therefore, as shown in FIG. 10, the draft gradient c is reduced to reduce the volume of the second sprue 9a, and the volume of the unnecessary non-molded product portion is reduced as compared with the conventional case, thereby saving the resin material. I can.

FIG. 11 shows a second embodiment of the present invention.

The same parts as those in the first embodiment will be described with the same reference numerals.

The second sprue molding part 19 of the second embodiment.
Is composed of a concave member 21 and a member 22 on the opposite side, and the shape of the second sprue 19a is substantially parallel to the side surface 18a of the concave portion 18 and the shaft 19 of the second sprue 19a.
The portion 19d near the recess and the portion 19e on the opposite side are asymmetrical with respect to the plane including c.

The volume of the portion 19d near the recess is made smaller than the volume of the portion 19e on the opposite side to avoid the recess 18.

In the injection molding die of the second embodiment, in addition to the operation of the first embodiment, when the recessed member 21 is processed, the shape of the tip of the recessed portion 19d is the first.
Since it does not have an arc shape as in the embodiment, the first
It can be processed more easily than the concave member 11 of the embodiment. FIG. 12 shows a third embodiment of the present invention.

The same parts as those of the first embodiment will be described with the same reference numerals.

The second sprue molding part 29 of the third embodiment.
Comprises a concave member 31 and a member 32 on the opposite side, and the shape of the second sprue 29a is substantially parallel to the side surface 28a of the concave portion 28 and the shaft 29 of the second sprue 29a.
A portion 29d near the recess and a portion 29e on the opposite side have an asymmetrical shape with a plane including c as the center.

The volume of the portion 29d near the recess is made smaller than the volume of the portion 29e on the opposite side to avoid the recess 28. The tip of the portion 29d near the recess is formed obliquely.

In the injection molding die of the third embodiment, in addition to the operation of the first embodiment, the tip of the recessed portion 19d of the recessed member 31 is formed obliquely.
It can be processed more easily than the concave member 11 of the first embodiment.

Further, the concave portion approaching member 11 of the second embodiment.
It is possible to reduce the flow resistance in the second sprue 9a as compared with. FIG. 13 shows a fourth embodiment of the present invention.

The same parts as those in the first embodiment will be described with the same reference numerals.

The second sprue molding portion 39 of the fourth embodiment.
Is composed of a concave member 41 and an opposite member 42, and the shape of the second sprue 39a is substantially parallel to the side surface 38a of the concave portion 38 and the shaft 39 of the second sprue 39a.
The portion 39d near the recess and the portion 39e on the opposite side have an asymmetrical shape with the plane including c as the center.

The volume of the portion 39d near the recess is made smaller than the volume of the portion 39e on the opposite side to avoid the recess 38. Then, a groove 43 is formed at a position facing the pin gate 13 formed on the opposite side portion 39e at the tip of the concave portion 39d.

In the injection molding die of the fourth embodiment, in addition to the operation of the first embodiment, the groove 43 is formed at the position facing the pin gate 13, so that the first embodiment of the first embodiment is improved. The flow resistance of the resin material is further reduced as compared with the two sprue 9a.

14 to 16 show a fifth embodiment of the present invention.

The same parts as those in the first embodiment will be described with the same reference numerals.

The recessed member 51 of the fifth embodiment is formed integrally with the stationary mold 50. The second sprue forming part 49 includes the recessed part member 51 and the opposite side member 52 that is inserted into the recessed part member 51 in a nested manner.
It is mainly composed of and.

A concave portion 48 corresponding to the convex portion 7b of the molded product 7 is formed in the concave member 51, and the second sprue 4 is formed.
The shape of 9a is substantially parallel to the side surface 48a of the recess 48, and a portion 49e on the side opposite to the portion 49d near the recess centering on a plane including the axis 49c of the second sprue 49a.
And have an asymmetrical shape.

The volume of the portion 49d near the recess is made smaller than that of the portion 49e on the opposite side to avoid the recess 48.

In the injection molding die of the fifth embodiment, in addition to the operation described in the first embodiment, a portion 49d near the recess is directly formed in the fixed side die 50. Therefore, as shown in FIGS. 15 and 16, the mold mark 53 formed around the gate mark 14 formed on the molded product body 7a is the mold mark 53 formed in each of the embodiments. It can be reduced compared to 54.

Therefore, the appearance quality of the molded product 7 is further improved as compared with the above-mentioned respective examples.

FIG. 17 shows a sixth embodiment of the present invention.

The same parts as those of the fifth embodiment will be described with the same reference numerals.

The recess side member 61 of the sixth embodiment is formed integrally with the stationary mold 60. Then, the second sprue molding part 59 includes the recessed part member 61 and the opposite side member 62 which is inserted into the recessed part member 61 in a nested manner.
It is mainly composed of and.

A concave portion 58 corresponding to the convex portion 7b of the molded product 7 is formed in the concave member 61, and the second sprue 5 is formed.
The shape of 9a is substantially parallel to the side surface 58a of the concave portion 58, and a portion 59e opposite to the concave portion 59d near the concave portion is centered on a plane including the axis 49c of the second sprue 59a.
And have an asymmetrical shape.

The volume of the portion 59d near the recess is made smaller than the volume of the portion 59e on the opposite side to avoid the recess 58.

The tip of the portion 59d near the recess is formed in a substantially conical shape having a taper.
As it goes upward, it has a circular cross-section along with the opposite portion 59e.

In the injection molding die of the sixth embodiment, in addition to the operation described in the fifth embodiment, the portion 59d near the recess is easily processed, and the injection molding die of the fifth embodiment is The flow resistance of the resin material passing through the inside of the sprue 59a can be further reduced as compared with the case of the two sprues 49a.

The embodiment has been described above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the present invention is applicable even if there are design changes and the like within the scope not departing from the gist of the present invention. Of course, it is included in.

For example, in each of the embodiments of the present invention, the mode in which the present invention is applied to the second sprue 9a of the two-stage sprue molding portion is shown, but the invention is not particularly limited to this, and the sprue of the one-stage sprue molding portion is used. As a matter of course, the sprue may be applied in any arrangement such as applied.

Further, in each of the embodiments of the present invention, the second sprue molding portion 9 and the like are divided into two parts such as the recess-side sprue molding portion 11 and the opposite side sprue molding portion 12, but not limited to this. If the second sprue molding portion 9 or the like is vertically divided along the shaft 9c or the like, the second sprue molding portion 9 or the like may be divided into four, or into two in a plane including the shaft 9c substantially perpendicular to the side surface 8b of the recess 8a. The second sprue forming part 9 and the like may be divided in any way such as by dividing.

[0058]

As described above, the above-mentioned claim 1
In the invention described in (1), the volume of the portion near the recess is made smaller than the volume of the sprue on the opposite side to avoid the recess, so that the sprue should be formed close to the recess. Can be done. Therefore, as compared with the conventional molded product, it is possible to form a gate mark near the convex portion and improve the appearance quality.

Further, in the invention described in claim 2, in addition to the effect of the invention described in claim 1, at the time of producing the sprue molding portion, the sprue inner surface is divided into a better state than in the conventional case. It is possible to improve the releasability even if the polishing is performed to a small degree and the draft is not taken so much. For this reason, there is a practically useful effect that the draft can be reduced, the volume of the sprue can be reduced, the volume of the unnecessary non-molded product portion can be reduced, and the resin material can be saved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an essential part showing an injection molding die of a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing the injection molding die of the first embodiment of the present invention.

FIG. 3 is a perspective view showing a molded product of the first embodiment of the present invention.

FIG. 4 is a plan view showing an opposite side member of the second sprue forming part according to the first embodiment of the present invention.

FIG. 5 is a side view showing the opposite side member of the second sprue molding part according to the first embodiment of the present invention.

FIG. 6 is a VI-VI sectional view of FIG. 5 showing the opposite side member of the second sprue molding part of the first embodiment of the present invention.

FIG. 7 is a plan view showing a recessed member of the second sprue molding portion according to the first embodiment of the present invention.

FIG. 8 is a side view showing a recessed member of the second sprue molding portion according to the first embodiment of the present invention.

FIG. 9 is a sectional view taken along the line IX-IX in FIG. 8 showing the recessed member of the second sprue molding portion of the first embodiment of the present invention.

FIG. 10 is a sectional view showing a second sprue forming part according to the first embodiment of the present invention.

FIG. 11 is a partial cross-sectional view of an essential part showing an injection molding die of a second embodiment of the present invention.

FIG. 12 is a partial cross-sectional view of an essential part showing an injection molding die according to a third embodiment of the present invention.

FIG. 13 is a partial cross-sectional view of an essential part showing an injection molding die of a fourth embodiment of the present invention.

FIG. 14 is a partial cross-sectional view showing an injection molding die of a fifth embodiment of the present invention.

FIG. 15 is an overall perspective view showing a molded product of a fifth embodiment of the present invention.

FIG. 16 is a plan view showing a mark of a die formed on a molded product of a fifth embodiment of the present invention.

FIG. 17 is a partial cross-sectional view showing an injection molding die of a sixth embodiment of the present invention.

FIG. 18 is a partial cross-sectional view of a main part showing a conventional injection molding die.

[Explanation of symbols]

 7 Molded product 7a Molded product body 7b Convex part 8,18,28,38,48,58,68 Concave part 9a, 19a, 29a, 39a, 49a, 59a Second sprue 9c, 19c, 29c, 39c, 49c , 59c Axis 9d, 19d, 29d, 39d, 49d, 59d Recessed part 9e, 19e, 29e, 39e, 49e, 59e Opposite part

Claims (2)

[Claims] 1. A molded product having a molded product main body and a convex portion protruding from the molded product main body, wherein a concave portion for molding the convex portion and a sprue tapered along the side surface of the concave portion. In the injection molding die having, the sprue has an asymmetrical shape with respect to a side surface of the recess and a portion on the side opposite to the recess centering on a plane including the axis of the sprue, An injection-molding die, characterized in that the volume of the portion near the recess is made smaller than the volume of the portion on the opposite side to avoid the recess. 2. A mold for injection molding, wherein the sprue molding portion forming the sprue is vertically divided along the axis of the sprue.